The present invention pertains to a hydraulic vibration isolation mount for automotive vehicle applications, in particular, and including a mechanism for selectively varying the volume of an orifice track between a pumping chamber and a reservoir of the mount to vary the vibration isolation characteristics of the mount.
Hydraulic engine and powertrain mounts have been developed which are generally characterized by a partition separating a fluid pumping chamber from a fluid reservoir, the pumping chamber being defined also by an elastomer mount body and the reservoir being delimited by a flexible diaphragm. Dynamic stiffness of the mount is determined by an orifice track formed in the partition for communicating fluid between the pumping chamber and the reservoir. Mounts have also been developed which include a decoupler exposed to fluid in the pumping chamber and/or the reservoir and operable to reduce damping of relatively low amplitude, high frequency vibrations.
In the development of hydraulic engine mounts for various vehicle applications, the ability to xe2x80x9ctunexe2x80x9d the mount to a particular vehicle without removing it from the vehicle would be particularly useful during the so-called vehicle ride or occupant comfort xe2x80x9ctuningxe2x80x9d or development phase of the vehicle development. In conventional vehicle ride development for a new vehicle design, for example, it is not unusual to create between ten and twenty specific mount configurations and variations, and swap each of these parts into and out of the vehicle during testing until the proper xe2x80x9ctuningxe2x80x9d or isolation characteristics of the mount are achieved. Still further, for certain mount applications, it may be desirable to substantially continuously vary the vibration isolation characteristics of the mount.
Accordingly, there is a strong desire to provide an engine or powertrain mount which may be easily adjusted without removing the mount from the vehicle for vehicle development purposes and also for use in applications where a so called active or semi-active mount is needed or desired. It is to these ends that the present invention has been developed.
The present invention provides an improved engine or powertrain mount of a hydraulic type which may be adjusted or xe2x80x9ctunedxe2x80x9d over a range of vibration frequencies to improve the damping or isolation characteristics of the mount and without removing the mount from its working position.
In accordance with one aspect of the present invention, a hydraulic engine mount is provided which includes a partition or orifice track assembly characterized by opposed orifice plates, an orifice track formed by one of the plates and a membrane interposed the orifice track and a substantially coextensive annular fluid chamber which may be filled with pressure fluid to deflect the membrane to change the volume and cross sectional area of the orifice track, thereby changing the mount vibration isolation characteristics. The annular chamber is in communication with an actuator for adjusting the volume of fluid in the annular chamber and the distortion or deflection of the membrane. In this way, the volume and cross sectional area of the orifice track may be adjusted to selectively vary the tuning or vibration isolation characteristics of the mount without removing the mount from its working position.
The configuration of the mount of the present invention may be such as to provide a so-called active or semi-active mount for production vehicle applications as well as a mount used for research or development purposes without requiring the construction of a large number of mounts with different fluid flow and vibration damping characteristics and without suffering the time required to assemble and disassemble the mount with respect to the structure supported thereby.
Accordingly, the invention reduces the number of prototype mount test iterations necessary during a mount and engine development project and improved vibration isolation characteristics may be determined through the ability to make direct comparisons of mount performance by selectively adjusting the so called dynamic stiffness of the mount.
Those skilled in the art will further appreciate the above mentioned advantages and superior features of the invention together with other important aspects thereof on reading the detailed description which follows in conjunction with the drawings.